The Wahoo Kickr comes with a separate cadence sensor that sends Bluetooth and Ant+ signals. You attach it to the left crank or your shoe. The Kickr has a built in power meter that sends Bluetooth and Ant+. Connecting sensors to a computer or Ipad requires something to receive the sensor signal, either BT on a Mac, or ANT+ on a Windows PC. The Ipad reads BT. BT needs to be version 4.0 so it will have to be a later iPad. It is also useful to have heart rate for training, so a ANT+ or BT chest strap.

A full setup for Zwift indoor training or other typical video software would be:
Bike
Smart trainer (resistance controlled by the computer for hills or wattage intervals)
Computer - Virtual worlds are graphically intensive so a good video card is required for high res.
Built in BT and/or ANT+ USB dongle
Subscription to software
Large screen connected to computer or iPad - nice for immersion
Speakers
Sweat mat
Fans
Heart rate strap
Internet connection - preferable to use ethernet over WiFi
Stand for monitor and iPad next to bike.

Join the Facebook group Zwift Riders to see people's setups. These training equipment configurations run into the thousands, above the cost of the bike.

Also watch the Youtube Zwift videos https://www.youtube.com/channel/UCeO...y65aiENWfuFzUQ which would be similar to any other indoor training software.